No errors reported when deployment fails

[timgent]

When a deployment fails with drone using this plugin the output is identical, no error is reported, and the build is marked as a success.

Suggestion is that upon successful deployment a message is added to the user viewable log on drone stating "application deployed successfully".

Upon failure an error should be displayed, if possible with a reason, for example "application deployment failed, message from kubernetes as follows:
......etc"

Also upon failure drone should not report a success :)